Such devices are used in particular for hydrating consumable produce set out on displays, in particular in supermarkets. By way of example, the produce may be fruit and vegetables.
Such devices comprise a vessel of liquid and spray heads arranged in the vessel, each head comprising a nozzle containing the liquid from the vessel and an ultrasound emitter suitable for emitting ultrasound waves into the liquid in order to spray it.
The liquid for spraying is generally water coming from a conventional mains water network.
However, as a function of the quality of the water and also of the quality of the surrounding air, the device is liable to become dirtied repeatedly. In particular, biofilms, i.e. films formed by bacteria at the surface of the water, are liable to appear in the vessel. These films constitute pockets encouraging the development of bacteria that, on being inhaled, are potentially harmful for man, e.g. Legionella. The development of such bacteria must be controlled in order to avoid them being projected into ambient air. Furthermore, internal development of the population of bacteria is encouraged by certain increases in the temperature of the water (the ideal temperature for the development of Legionella lies in the range 25° C. to 45° C.), by adding a volume of contaminated water, or indeed by injecting contaminated air. More generally, the dirt that accumulates in the device can lead to malfunctioning.
The operations needed for cleaning the device are relatively burdensome and may require the machine to be dismantled, at least in part. This also applies when it is desired to clean the machine after it has been stopped for a long period of time.